Though radioactivity is widely used in bioassays due to its high sensitivity and convenience, safety and environmental concerns have accelerated efforts to eliminate its use. Recent procedures using luminescence have often surpassed conventional isotopic methods; among these the luminescence of firefly luciferase is the most efficient. Relevant biomedical applications include reporter gene technology, viral and cell tracer methods, non-isotopic immunoassays and other probe technologies, and clinical biomass/viability assays. Through fundamental research on the enzymatic mechanism of beetle luciferases, Promega Corporation has developed new chemistry which provides greater luminescence intensity with simpler reaction kinetics. To better understand the commercial potential of beetle luciferases and to develop specific enzymes suited for applications, Promega is currently examining the structure and function of several adult-form isozymes. This proposal is for extending our investigations to include a new class of isozymes derived from embryonic and juvenile developmental forms of elaterid beetles. These isozymes are spectrally unique, and taxonomic data reveals that they are evolutionarily divergent. Yet, due to inaccessibility, these enzymes have never been investigated biochemically. In Phase l, genes encoding these novel isozymes will be isolated to allow for enzymological and physical studies of the recombinant enzymes planned for Phase II.